Isokawa Muneki, Nakanishi Kanki, Kanamori Takahiro, Sekiguchi Tetsushi, Funatsu Takashi, Shoji Shuichi, Tsunoda Makoto
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
Department of Nanoscience and Nanoengineering, Waseda University, Tokyo 169-8555, Japan.
Anal Chem. 2024 Jul 9;96(27):11002-11008. doi: 10.1021/acs.analchem.4c01669. Epub 2024 Jun 13.
The chemical derivatization of target analytes can enhance the sensitivity and selectivity of separation-based methods for metabolite analysis using microfluidic devices. However, the development of chromatography-based microfluidic devices with integrated derivatization units is challenging. In this study, a novel derivatization unit with a pillar array (PA)-based mixing channel was developed for postcolumn derivatization during on-chip liquid chromatography (LC). The PA mixer enhanced mixing between the derivatization reagents and analytes in the transverse direction, while preventing analyte dispersion in the flow direction. After the concept was confirmed using computational fluid dynamics analysis, microfluidic devices with a LC column and PA mixer were fabricated on a 20 × 20 mm silicon plate. Fluid experiments were performed using a PA mixer with a pillar size of 5 or 10 μm or a hollow-channel mixer, which revealed that the PA mixer enhanced transverse mixing without increasing the width of the analyte peak. Moreover, the developed device enabled the analysis of three amino acids within 40 s by separation via hydrophilic interaction chromatography followed by postcolumn fluorogenic derivatization with naphthalene-2,3-dicarboxaldehyde and fluorescence detection. Our results demonstrate the potential of integrated derivatization units for the development of micrototal analysis systems for use in bioanalysis.
